The manufacturing of circuit boards involves many processes, one of which is screen printing solder paste and adhesives onto printed circuit boards so that electronic components can be placed onto the boards. Screen printing of solder paste is typically performed in a printer. The circuit board is mounted on a conveyor for insertion into the printer. The board is moved into the printer for printing of the solder paste onto the circuit board.
To apply solder paste and surface mount components to a surface of a circuit board, several actions are taken using a stencil. The stencil has one or more (typically more) apertures that define a pattern corresponding to a pattern of pads already disposed on the circuit board. The stencil is placed substantially parallel to the surface of the board to be printed and the apertures are aligned with the pattern on the substrate surface. The solder paste or other material to be deposited is placed on top of the stencil for deposition into the apertures and onto the board. Once the apertures are filled with material, excess material may be removed from the top of the stencil, using for example a squeegee, so that substantially all of the material that remains is in the apertures. The stencil is separated from the board and the surface tension between the board and the material causes most of the material to stay on the board.
Circuit boards come in a variety of standard sizes and solder printers are typically configured to accommodate a range of various sizes up to and including boards of about 24″×20″. For example, printers exist that can accommodate boards up to about 24″×20″, up to about 0.5″ thick, and up to about 80 pounds. Equipment, e.g., for holding and positioning the boards, and for applying solder paste to the boards, influence the sizes of boards that a printer can accommodate. For example, squeegees for applying solder paste are typically about 24″ to accommodate a 24″ substrate while providing desirable characteristics for spreading the solder paste. Some specialized printers exist for printing on larger substrates such as 36″ substrates. Some concerns with accommodating larger boards is that quality may degrade, and/or solder paste waste may increase, compared to printing smaller boards, e.g., due to using larger non-standard squeegees. Another concern regarding the size of boards that a printer can accommodate is the width of the printer itself. As the printer gets wider, a production line using the printer gets longer. As production lines are often tightly fit to available space, widening a printer may have significant practical implications upon a production line using the printer.